[RWP] Tweaking Synth Parameters

[Indigo]

Hi Folks,
Running Window-Eyes, When I load a VST synth, and, in the effects screen, 
left click on the word Param at the number pad, I get a context menu at the 
arrow keys with Show Parameter List F.
If I hit F,... then hit the letter S, for Show at Track, I arrow down and 
sometimes find a long list of the synth's parameters, either at the arrow 
keys or sometimes at the bottom of the number pad screen.
Once or twice, I clicked on Learn, then turned a knob on my midi keyboard 
and heard a change in the synth's sound, but usually no amount of knob 
turning on my midi keyboard or pushing buttons on the qwerty keyboard causes 
any change of parameter values.
I tried the dash and equals keys someone here suggested, no joy.
What am I doing wrong?
We must have some standard way to change values in either synths or effects 
plugs, don't we?
Thanks for any suggestions,
Indigo